Display screen or portion thereof with a graphical user interface



The FIGURE is a front view of a display screen or portion thereof with agraphical user interface showing the new design.

The outermost broken line rectangle shows the display screen or portionthereof, and forms no part of the claimed design. All other broken linesshow portions of the animated graphical user interface and form no partof the claimed design.

CLAIM I claim the ornamental design for a display screen or portionthereof with a graphical user interface, as shown and described.